Alternative Infrastucture


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a short presentation a colleague and me threw together for a lecture

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Alternative Infrastucture

  1. 1. Alternative Infrastucture if we do it, we might as well do it right
  2. 2. Experiments Twitter clone "retwis":     Key Value Store: redis     Web Framework: sinatra Mediawiki:     Webserver: Nginx (!= Apache)     PHP: php-fpm (!= mod_php)
  3. 3. Retwis-RB "An example Twitter application using the Redis key-value database" --> sinatra redis require 'rubygems' require 'rubygems' require 'sinatra' require 'redis' get '/hi' do     "Hello World!"  r = end puts "set foo to bar" r['foo'] = 'bar'
  4. 4. Redis Benchmark root@keyvalue:~# redis-benchmark -q SET: 105273.69 requests per second GET: 107526.88 requests per second INCR: 95238.10 requests per second LPUSH: 121987.80 requests per second LPOP: 108728.26 requests per second PING: 133386.66 requests per second
  5. 5. testing @ HdM CPU: 100% httperf             57% redis-server 40% ruby1.9.1    Durchsatz: 6 req/s         Ò_ó
  6. 6. Context Switches? ?!
  7. 7. server -> home ->
  8. 8. Home Tests: httperf --server=localhost --port=4567 --uri=/test --num- conns=100 --num-calls=50 Webserver: "thin" EventMachine: a library for Ruby, C++, and Java programs. It provides event- driven I/O using the Reactor pattern
  9. 9. single connection home Total:  Request rate 56.7 req/s connections 1 (17.6 ms/req) requests 500 Reply rate min 41.6 [replies/s] avg 41.6 replies 500 max 41.6 Reply time response 17.6 [ms] transfer 0.0 Reply status: 1xx=0 2xx=500 3xx=0 4xx=0 5xx=0 test-duration 8.824 s
  10. 10. 100 connections home Total: Request rate 48.5 req/s connections 100 (20.6 ms/req) requests 5000 Reply rate min 16.2 replies 5000 [replies/s] avg 48.7 max 71.6 Reply time response 20.6 [ms] transfer 0.0 Reply status: 1xx=0 2xx=5000 3xx=0 4xx=0 5xx=0 test-duration 103.160 s
  11. 11. 2nd Experimental Setup Replacing  Apache+mod_php by  Nginx+PHP-FPM
  12. 12. Nginx ... is... a lightweight Web Server a Reverse Proxy an IMAP/POP3 proxy   used by 14,988,610 domains today implmented by larges sites as WordPress, Github, SourceForge etc.  
  13. 13. Nginx vs Apache Apache process based each connection requires a new thread high concurrency     -> high memory usage     -> CPU overhead (e.g. context switches) PHP is usally included in Apache Web Server as module (mod_php)   Nginx fork of apache 1.3 with the multi-processing ripped out in favor of an event loop asynchronous model (event based) uses only one thread for all connections (master thread) PHP is used as seperate process over FastCGI (PHP-FPM) Web Server and PHP-FPM are used as seperate applications communication via TCP-connetions or Unix-sockets         -> little overhead due to communication costs
  14. 14. Event Loop What is an event loop? usually you write code like: var result = db.query("select.."); result.do_something(); but an event loop looks like: db.query("select..", function (result) { result.do_something()});
  15. 15. Motivation Apache+mod_php compared to Nginx+php-fpm (comparison made by Boštjan Škufca - 5 Different scenarios HelloWorld.php – simple echo of “Hello, World!” (13 bytes), HelloWorld.txt – static file with “Hello, World!” (also 13 bytes) 100KB.txt – static content 1MB.txt - static content index.php – more complex site with several DB-queries, HTML template parsing… Tests with keepalive-feature [-k] and without keepalive (same socket can be used for request and response)
  16. 16. Benchmark Setup Benchmark tests conducted using ApacheBench ab -n NREQ -c NCONC [-k] http://server.domain. com/bench/FileName NREQ is the number of requests: - HelloWorld.php: 500000 - HelloWorld.txt: 500000 - 100KB.txt: 500000 - 1MB.txt: 50000 - AppFront: 5000 NCONC = number of concurrent requests 1 ,2,4,8,16,32,64,128,256,512
  17. 17. PHP-generated Hello World! Apche is always faster than Nginx This demonstrates the overhead of the communication between Nginx and PHP- FPM
  18. 18. Static Hello World! Nginx with keepalive is more than twice as fast as Apache This demonstrates the overhead that is caused by creating TCP-connections
  19. 19. Static 100kb.txt File This test should demonstrate a „real world “ example of a static page request Again, Nginx is twice as fast as Apache
  20. 20. 1MB.txt File This test demonstates a more complex file transfer Keepalive was not tested, because the file size is so large that TCP-connections aren‘t important Nginx is just slightly better
  21. 21. Application Frontpage (index. php) Again a „real world“ example with a more complex PHP-site Nginx is just slightly better
  22. 22. Apache PHP vs TXT Dynamically generated content and static content are nearly equally fast
  23. 23. Nginx PHP vs TXT Nginx serves static content twice as fast as dynamic content
  24. 24. Additional Comparison
  25. 25. Conclusion When is it worth to use Nginx? If you have limited hardware resources (e.g. on VPS) If you have a lot of static content
  26. 26. Further Alternative Nginx works as reverse proxy static content is passed by Nginx (e.g. Pictures) dynamic Content will be forwarded to an Apache        behind the proxy advantages: static content will be returned very fast slow user connections do no longer hold resources, because the "blocking" connection is now between Nginx and Apache; not the user and Apache
  27. 27. our problems mysql dumps: create dump + copy dump + insert dump = hours loadtesting: client == server --> no testing for high concurrency, no isolation of variables. client too slow  different configurations keepalives Nginx workers/processes vs apache threads/clients ...